RISK-FACTORS FOR BREAST-CANCER MORTALITY AMONG THE NATIONAL BREAST SCREENING STUDY OF CANADA PARTICIPANTS

We studied the relationship between risk factor information and breast cancer mortality by means of a case control study, nested within the population of the National Breast Screening Study of Canada (NBSS). Th e characteristics of women aged 40-59 years, identified at the initial screen, who subsequently died of breast cancer up to 7 years from the initial screen, were compared with those of controls drawn from the s ame population. Among the factors evaluated in this study, number of l ive births and presence of symptoms in the breast revealed on direct q uestioning were found to be significantly related to breast cancer mor tality. The results suggest a decrease in risk of dying of breast canc er associated with one or more live births (OR: 0.79, 95% CI: 0.68, 0. 93), and an increase in risk of dying of breast cancer associated with symptoms in the breast revealed on direct questioning at the initial screen (OR: 2.01, 95% CI: 1.20, 3.37).